In this video only on five you can -- the fresh carcass of a -- back -- Boston Harbor. This one is a male about fifty feet long but only about 10% of its body is above water. The -- back was first spotted early Sunday within hours biologists from the New England Aquarium were on the Coast Guard cutter examining and marking the whale. -- -- -- is the spokesman for the aquarium. When I think that biologists on the animal waste that there was also a lot of bruising and a lot of what we -- pressure lines laterally can be a product that something happened around it. Then back -- or an endangered species and are not normally seen in the harbor because it is not their natural habitat. But they are common that still -- -- national marine sanctuary east of Boston. So the obvious question is how and why did this whale wind up dead in Boston Harbor. This animal most likely probably -- -- -- he probably was already dead it was either -- in the tide. Or there you know it's possible that if it was a -- strike. He could have been brought -- ship.

This transcript has been automatically generated and may not be 100% accurate.

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